A sealed-type alkaline storage battery is known in the art which includes a negative hydrogen-occlusion electrode made of a hydrogen-occlusion alloy capable of reversibly occluding and releasing hydrogen. The battery additionally includes a positive electrode made of nickel oxide or the like stacked in relation to the negative electrode in a laminate fashion with a separator interposed between the two electrodes. This electrode assembly is then placed in a container followed by the pouring of an alkaline electrolyte into the container and attachment of a cover to the container in a manner to hermetically seal the container. Since this type of sealed storage battery is pollution-free and has a high energy density, it has recently attracted attention as possibly replacing conventional nickel-cadmium storage batteries.
A hydrogen-occlusion electrode is considered advantageous in that, while allowing for the construction of a storage battery in the same manner as when a conventional cadmium electrode is used, a hydrogen occlusion electrode provides a greater energy density of actual usable discharge capacity. Hydrogen-occlusion alloys, such as LaNi.sub.4.5 Al.sub.0.5, LaNi.sub.4.0 Co.sub.0.5 Al.sub.0.5, or the like, are suitable for making a hydrogen-occlusion electrode.
However, when utilizing a conventional method of manufacturing a sealed-type storage battery using a hydrogen-occlusion electrode, it has been found that when an electrolyte is poured into the container holding the electrodes and charging is carried out, that the metal content present in the hydrogen-occlusion electrode becomes eluted in the electrolyte. This is especially the case when the hydrogen-occlusion electrode is made of a hydrogen-occlusion alloy containing cobalt (Co) as one of the metal elements The elution of the electrode by the electrolyte results in a change in the composition of the alloy and causes an oxide of the metal to form a film on the surface of the alloy. As a result, the internal pressure of the battery rises to the extent that the battery's safety valve is actuated to release the excess pressure of the gas whereupon the electrolyte is also partially released with the gas resulting in loss of the electrolyte and a shorter life for the battery. Additionally, following assembly of the battery, it is not possible to charge the battery uniformly since the electrodes are not uniformly impregnated with the electrolyte. A storage battery manufactured using a conventional manufacturing process, therefore, is subject to the disadvantages of having a comparatively smaller capacity, a shorter cycle life, a greater capacity loss under a high- or low-temperature condition, and a higher internal pressure at the time of an overcharge operation.